Functional Analysis Of Rice LOB7 Gene And Evolutionary Analysis Of CCT Gene Family Among Four Species

Rice is the main food for more than half of the world population. It is very essential to elucidate the developmental mechanisms of rice, in purpose of breeding high yield varieties to meet the demands of huge population growth. Leaves are the predominant photosynthetic organs and also the main factors for rice yield potential. LBD genes were a class of plant-specific transcription factor, which defined a boundary between the meristem and the leaf.LOB7, located on chromosome 3, was one of the members of rice LBD family. When LOB7 was overexpressed, the observed plant phenotype was dwarf with severe curly leaves, small leaf angle, and leaves were of dark green. Further research found that, tiller and crown root number of LOB7 overexpressed plant (OE) increased significantly compared to the wild type, while inhibition of LOB7 caused less tillers and crown roots than the wild type. In order to know the role of LOB7 in BR regulatory pathway, we have soaked the leaves and leaf sheath junction point of OE and wild-type plants with brassinolide, and observed the leaf angle of wild type changes greatly while the OE plant kept still, indicating that LOB7 might be involved in BR regulation pathway. Further more, we examined the expression of PIN auxin transport genes with LOB7 overexpressed plants. Significant changes were detected for the number of PIN genes indicating the role of LOB7 during auxin transportation. This was consistent with phyllotaxis change phenotype of LOB7 overexpression plant. Thus LOB7 might be involved in auxin and BR cross-talk, thereby affecting the growth of rice.The CCT domain defines a conserved 43-45 amino acids of the 3’ region of CONSTANS, CO-like, and TOC1.The plant specific CCT gene plays a role in light signaling and regulation of photoperiodic flowering. Meanwhile, the evolutionary relationship among family members has not been well studied.In this study,97 CCT domain containing genes were isolated in four complete sequencing and annotation genomes. Analyses of corresponding protein structure and genetic relationships showed that CCT domain containing protein genes kept a wide range of variation within and among different species, CCT family sizes were increased by chromosome duplication. CCT gene family was classified into four subgroups according to the CCT domain. One sub-group gathered most of the grass CCT gene, which might be specially involved in the regulation of flowering time. The expansion of gene family members, variation of protein structures and gene expression patterns comprehensively caused functional diversity within and among the species.